1. Field of the Invention
The present invention relates to a film viewer which pulls developed film out of a film cartridge so that the film can be observed.
2. Description of the Related Art
A plastic film cartridge of an Advanced Photo System (APS) has been proposed in newspapers, etc., which contains photographic film and is smaller than a conventional film cartridge which houses 135 film.
The above-mentioned film cartridge is provided with a shutter (a light-shielding lid) which can be opened at a film pull-out opening thereof. Before and after the film is exposed, the entire film leader is wound in the cartridge, and the light-shielding lid is closed. When the user mounts the film cartridge on the camera, the light-shielding lid is opened, and the film is pulled out. The user brings the film cartridge to a processing laboratory to develop the film. After the processing, the processing laboratory returns the film in the film cartridge to the user.
A visual exposure index is provided on the film cartridge to inform the user whether the photographic film is unused, the film is being exposed, the film has been exposed, or the film has been developed. That is, as shown in FIG. 14, four marks (openings) 2 (unused), 3 (being exposed), 4 (having been exposed), and 5 (having been developed) are formed on an end face 1A of a film cartridge 1 around a spool 6, and these four marks have different shapes. A sectorial white plate 7 of which central angle is 60.degree.-90.degree. is provided at the inside of the marks (openings) 2-5, and it is positioned at one of the openings 2-5. The white plate 7 rotates together with the spool 6.
When the white plate 7 is positioned at the opening 2 for example, the circular opening 2 is displayed in white to indicate that the film cartridge 1 contains the unused photographic film. When the white plate 7 is positioned at the semi-circular opening 3, the opening 3 is displayed in white to indicate that the film cartridge 1 contains the film which is being exposed (the film has been partly exposed). When the white plate 7 is positioned at the cross-shaped opening 4, the film cartridge 1 contains the exposed film. When the white plate 7 is positioned at the square opening 5, the film cartridge 1 contains the developed film.
An undevelopment indicating chip 8 is provided on the end face 1A of the film cartridge 1. The chip 8 indicates that the film contained in the film cartridge 1 has not been developed, and the chip 8 is broken at the processing laboratory when the film is developed.
According to the above-described film, when the user asks for additional prints, he or she cannot observe the frame images through a negative film sheath as in the past. Thus, a film viewer in which a film is pulled out of the cartridge is required for observing the frame images.
A conventional film viewer has a disadvantage because a film feed unit consisting of a cartridge chamber for containing the film cartridge, a film feed device for feeding the film, a film takeup chamber including a takeup spool for taking up the film fed from the cartridge, or the like must be designed and manufactured individually for every model of the viewer. Thus, it was difficult to provide a general-purpose film viewer at a lower price.
Since the film viewer is used for observing the images on the developed film, the developed film is used in the film viewer. When a film cartridge containing the undeveloped film is mounted on the film viewer, however, the film must be prevented from being pulled out.
In the case of a high-quality film viewer provided with an on-board microcomputer, etc., after the cartridge is mounted, an encoder provided on the other end 1B of the cartridge 1 is read. If the encoder indicates that the film contained in the cartridge 1 is undeveloped, an alarm, etc. can inform the user that the film cartridge containing the undeveloped film has been mounted.
In order to provide a general-purpose film viewer at a lower price, the use of the expensive parts such as the microcomputer should be avoided.